Thermal relay



iatented den., lll? 392530 stavas TBIG dr MAETUEACTURING COMPANY,

passerar, menar;

application med nevemeer ei, reas. serier navaseo.

My invention relates to temperature control devices and particularly to thermal rela s.

:lne ob ect of my invention is to provide a relatively simple thermal relay that shall be lefiective to control the temperature of an energy-translating device Within a relatively narrow and adjustable range.

Another object of my invention is to provide' a thermal relay that shall comprise a4 plurality of thermally actuable elements operable at difierent temperatures and co-acting to control a circuit Within relatively narrow temperature limits.

lin practicing my invention, I provide a main and an -auxiliary thermostat, each having a relatively large temperature dlfierential and actuated With a snap action, means :tor efiecting mechanical actuation of one of said thermostats by the other, and an auxiliary heating element energized 1n accordance vvith the position of the main thermostat.

lin the single sheet of drawings-Z o Figure 1 is a vievv in side elevation., with portions thereof shown in section, of a device embodying my invention.

Fig. 2 is a view in lateral section therethrough taken on the line II-Ill of Flg. 1, and

Fig. 3 is a schematic diagram of connections and of the device embodying my invention. v

thermal relay 11 comprises a pair of spaced plates 12 and 13, each ot a suitable electric-insulating material and shovvn as substantially rectangular or square in shape. The two piates are maintained in spaced relation by a plurality of bolts 14, Which may be located in peripheral angu'lar relation relatively to each other, and are here shown as being located in the corners of the plates 12 and 13. Each of the bolts 14; projects through a pair of tubular spacing members 15 and 16 that are efiective to maintain the plates in suitable predetermined positions relatively to each other.

The plate 12 is provided With a centrally located rod 17 that has one portion thereo extending toward the plate 13. A bimetallic element 18., of substantially disc shape is loosely mounted on the member 17 and held thereon in a pre-determined position by a pair of co-operating nuts 19 that are adapted either to fit tightly on the threaded portion oi the member 17 or that are provided with lock nuts (not shown) to hold them in predetermined s aced positions. The disc 18 is provided With two sets of co-operating contact members 21 and 22 that are so mounted on theV disc in diametrically opposed positions that the outer sur-faces thereof may move sufliciently on the supporting means to permit them to engage fixed contact members to be hereinafter described..

A guide pin 20, having one end thereof secured to the plate 12, so extends therefrom that its other end projects through an aperture a located in the disc 18. Thus turning of disc 18 on the member 1? is prevented and positive engagement of the contacts carried thereby Tvvith their respective stationary Contacts is ensureda A. pair ot fixed and co-operating contact members 23 and 24 are mounted on the plate 12 in such position that portions thereof Will be operatively engaged by the respective contact members 21 on the disc 18 When the disc has the shape illustrated in Fig. 1 of the dravving. Any suitable or desired construction of the substantially fixed contact members 23 and 241: may be employed in a manner Well lrnovvn in the arta An auxiliary birnetallic disc 25 is supported from theplate 13 by a supporting etern or pin 26 that is Secured thereto, the disc 25 being loosely mounted on the stem or pin 26. The disc 25 is provided with a pair of contact members 27 and 28 that are adapted to operatively engape relatively iixed contact Imembers 29 31 that are supported on the plate 13 and are located in such position as to be engaged hv the contact members 2? and 28 vvhen the disc 25 has the shape illustrated in Fig. 1 of the dravving.

A guide pin 3G, having' one end thereo suitably Secured to the platel, so extends 'thereiirom that its other end projects through an aperture Sila located in the disc 25. Thus, turning oi the disc 25 on the member 26 is prevented, and positive engagement oi the stationary contacts carried thereby With their respective stationary contacts is ensured.

Auxiliary contact members 82 and 33 are provided intermediate the tvvo plates 12 and 13 and are supported by suitable members 34 and 35 that have a portion thereof located on the rods 14 and tightly gripped between the respective tubular portions 15 and 16 hereinbefore described. The contact members 32 and 33 are adapted to be engaged by the co-operating contact members 22 on the disc 18 When the disc has moved to the position illustrated by the broken lines in Figs. 1 and 3.

Means for causing movement of one of the discs by means of the other bimetallic disc comprises a -tubular member 36 that is loosely mounted on a supporting member 37 which is, in turn, monnted on and supported by the inner end of the member 17. member 37 may be in the form of a small pulley, the hub thercof being provided with internal screw threads in order to permit of adjusting it on the member 17, or the usnal nuts may be located on the screw threaded art of the member 17 to permit of properly coat-ing the member 37.

Fig. 3 of the drawing illustrates the connections employed with the device embodying my invention and also illustrates an auxiliary heating element 38 that is adjacent to and in heat-interchangin;r relation with the disc 25. A' main heating element 39 is adapted to be controlled by the hereinbefore described thermal elements.

Referring to Fig. 3 of the drawing, the

parts of the device are shown in the posiconstructed that there is a relatively large temperature differential, or difference ln temperature, between the respective operative positions thereof. In other words, an undeformed thermostatic element will detlect from one position to another substantially directly in a-ceordance with Variations inthe temperature thereof, whereas a thermostatic -i element of the kind disclosed in the hereinbefore mentioned patent will deflect from an initial position to another position with a lsnaiz motion because its sha e chan es abruptly at a prede'termincd temperature of relatively high value and will remain in this V position until a relatively large temperature decrease has oceurred, whereupon it will again change its form abruptly and return to the original or initial position. Hence, such a thermostatic element, by itself, will be unable to control an electric heating circuit to therebyy maintain a desired temperature Within relatively narrow limits.

- Let it be assumed that We desire to control the temperature between the limits of C. and 7 6 C. The disc 18 should be one which is actuated from the position shown by the full lines in Fig. 3, at 76 C., and w-hich returns to that position when the temperature has been reduced to 50 C.

The'

Lassen? 100 C. and which returns to that position when the temperature has dropped to 7 5 C. The particular values of'the lower actuating temperature of disc 18 and the higher actu- .ating temperature of the disc 25 are immaterial, so llong as the values of the higher actuating temperature of disc 18 and the lower actuating temperature of disc 25 are substantially in accordance with those hereinbefore mentio'ned in order to obtain proper operation.

If the two discs have been properly adjusted and if the temperature rises to 76 C., disc 18 will be actuated to the position shown by the broken lines in Fig. 3 thereby interrupting the cireuit throufrh the main heating element 39. lVhen the sition the contact members 22 will engage the the auxiliary heating element 38. The energization of the auxiliary heating element 38, located adjacent to the disc 25, will cause a rapid increase in the temperature of the disc When the temperature of the disc 25 has been increased' to substantially 100, er to its upper temperature limit, it will be actuated to the position :illustrated by the broken lines-in Fig. 3, Whereby the cireuit through the auxiliary heating' element 38 is interrupted.

' When the disc 18 has been actuated to the positionv illustrated by the broken lines, it engages the, member 36, and the contact members 22, carried by the disc, engage the relatively stationary contact members 32 and .33. thus effect-ing energization of the aux'iliary heating element 38. Upon the energization of the heating element 38, the disc 25 becomes so 'heated that 'its shape changes abrnptlyto cause it to assumel theposition illustrated by the broken lines. Asthe'dise 25 moves to the position illustrated bythe broken lines, the disc 18 is moved to its fullline position by means of the member 36 which is actuated by the disc 25, thereby interrupting the circuit of the resistor element 38 and etl'ecting de-energization thereof.

Both the main and the auxiliary heater are now dc-energized and the temperature of the room or that of the chamber in which the thermal relay and the main and the auxilial'y heating elements are located will be disc 18 is in this pof Int) los'

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ferential, that are so electrically and mechanically co-ordinated and combined as to be operable inresponse to a relatively small temperature change or differential, Whichdifferential may be made of any predetermined range or value. As it is possible to so form or shape the thermostaticidiscs that they will be operable between predetermined temperature limits, itis possible to combine two such discs having different temperature limits of operation and each having a relatively large temperature differential, and to effect the control of a circuit in response to temperature changes within predctermined limits.

It is obvious that While I have illustrated and described the device as applied to an electric heating element. the 'device is not limited thereto but may be employed in connection With any other form of ener translating device or for the control of temperature Within any predctermined limits. The device embodying my invention Will operate equally as Well lin refrigerator control, as .it Will in the control of relatively high temperatures.

Various modificat-ions may be made in the device embodying my invention Without depaiting frdm the spirit and scope thereof and all such modifications are intended to be covered by the appended claims.

I claim as my invention:

l. fn a temperature controlling device,

the combination With a thermally-actuable means having a predctermined temperature difierential between its off and on position, of a second thermally-actuable means, energized in accordance With the position of the first-named thermally actuable means, for returning said first named thermally-actuable means from one of said positions to the other.

2.'n a' temperature controlling device, the combination With a plurality of opposed hermally-actuable devices located in spaced relation, one of said devices being energized in accordance with the position of the other, of means loosely mounted between said devices for permitting turn the other device to its normal position".

3. In a temperature controlling device, the combination with a thermostatic member operative at a predctermined temperature to interrupt an energizing circuit and .having a relatively large temperature differential between Operating temperatures, of a second thermostatic member, having a relatively large temperature differential between Operating temperatures and operativa ary said one device to reat a predctermined temperature higher than said first thermostatic member for effecting return of said first thermostatic member at a temperature variation that is less than its temperature differential.

' In a temperature controlling device, the combination With a thermally-actuable means having a predctermined temperature differential, of a second thermally-actuable means, a heating means for energizingsaid second thermally-actuable means uponoperation of the first thermally-actuable means, and means,'actuated by said second means, for returning said first means to its original position irrespective of said temperature differential.

5. In a temperature' controlling means, a

main and an means, each other, and an auxiliary heating means energized in accordance With the position of said main thermall -actuable means for modifying the operation of the auxiliary thermally-actuable means.

6. lin a temperature-controlling means, a main thermally-actuable means, an auxilithermally-actuable means opposed to said main thermally-actuable means, and an auxiliary heating means, energized in acco'rdance With the position of said main thermally-actuable means, for modifying the operation of the auxiliary thermally-acauxiliary thermally-actuable 'tuable means.

7. l'n a temperature-controlling means, a main thermostat, an auxiliary thermostat, and means mounted therebetween for permitting said main thermostat to open freely and for causing the opening of the auxiliary thermostat to effect 'the closing of the main thermostat.

8. main -thermostat, an auxiliary thermostat, means mounted therebetvveen for permitting said main thermostat to open freely and for causing the opening of the auxiliary thermostat to efi'ect the closing of the main thermostat, and heating means, energized in accordance with the position of the main thermostat, for efiecting actuation of the auxiliary thermostat.

9. in a, temperature-controlling means, a plurality of thermally-actuable means for controlling an electric Circuit, each having a relatively large temperature diderential between its operative positions and connected in series electric Circuit relation relatively to each other, and mechanical means located between said thermally actuable means for causing said thermally-actuable means to control said circuit Within predetermined temperature limits.

10. In a temperature-controlling device, the combination With a thermostatic member operable at a predctermined temperature to interrupt an electric circuit and to re-estabconnected in series circuit relation to In a temperatnre-controlling means, aI

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lish said circuit at a second predetermined temperature, of a second thermostatio member responsive to a temperature higher than said second predetermined temperature for actuating said 4first thermostatie member to its circ-uit-establishing position before said second predetermined temperature obtains in said first thermostatio member.

11.' The combination with a thermostatio member aetuable from an initial position to another when a predetermined temperature I of a relatively high value obtains therein and ret-urnable to said initial position when a seeond predetermined temperature of a relatively low value obtains, of means for causing said thermostatie member to return to its initial position when a 'temperature obtains in said member that is intermediate said relatively high and low temperatures.

12. The combination with a thermostatie member actuable from an initial lposition to another when a predetermined temperature of a relatively high .value obtains therein and returnable to said initial position When a second predetermined temperature of a relatively low value obtains, of thermostatie means for oausing said thermostatie member to return to its initial position when a temperature obtains in said member that is intermediate said relatively high and low temperatures.

13. The combinationlwith a thermostatic member actuable from an initial position to anotherI When a predetermined temperature of a relatively high value obtains therein and returnable to said-initial position when a second predetermined temperature of a relatively lou1 value obtains, of automatic means for causing said thermostatid member to return to its initial position when a temperature obtains in said member that is intermediate said relatively high and low temperatures. i

14. The combination with a thermostatic member actuable from an initial position to another when a predetermined temperature of a relatively highvalue obtains therein and returnable 4to said initial positionwhen a second predetermined temperature of a' relatively low value obtains, of thermostatio means controlled by said thermostatie member for causing said thermostatio member to return to its initial position When a tempera ture obtains in said member that is intermediate said relatively high and low temperatures.

In testimony whereof, I have hereunto subscribed my name this 16th day of Nov..

HOWARD D. MATTHEWS. 

